Overcast System for Mine Ventilation

ABSTRACT

An overcast system to block an intersection between two or more mine passageways so as to prevent the mixture of intake air with return air. The overcast system includes a first sidewall formed of one or more prefabricated panels, a second sidewall formed of one or more prefabricated panels, and a top member formed of one or more prefabricated panels, such that the top side spans the width between the first sidewall and the second sidewall. A fire-resistant coating is applied to at least a portion of the first sidewall, the second sidewall, or the top member to provide an air-tight, fire-resistant structure. Each of the one or more prefabricated panels is formed from a composite material having one or more structural studs embedded at least partially therein.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/272,748, filed Dec. 30, 2015, the disclosure of which is herebyincorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure relates to an overcast system used in mineventilation that prevents the mixture of ventilation air at anintersection of two passageways within a mine. More specifically, thepresent disclosure relates to an overcast structure formed of aplurality of prefabricated panels and coated with spray-on material tocreate a substantially air-tight and fire-resistant structure.

Description of Related Art

In underground mining operations, there is a need to provide aventilation system such that clean intake air may be introduced into themine through a first passageway (or passageways), while contaminatedreturn air may be removed via a separate, second passageway (orpassageways). As the return air may contain methane, dust, or othercontaminants, it is important that the intersection between these intakeand return air passageways be blocked through the use of an air-tightpartition and/or ducted via an overcast or undercast structure so as toprevent mixture of the ventilation air between the two passageways.

Previously, structures constructed of concrete block or steel plateswere used to define the respective passageways. These structures weretypically sprayed with sealants in an effort to form an air-tightpassageway. However, these structures require large amounts of materialand many hours of labor to construct. Furthermore, due to the numerousjoints between adjacent concrete blocks and/or steel plates, air leakswere common, leading to both contamination of the respective passagewaysand loss of pressure throughout the ventilation system.

Efforts have been made to both simplify the installation process ofpartition structures and provide for better air sealing betweenpassageways. For example, U.S. Pat. No. 5,879,231 discloses an overcaststructure formed, in part, from a plurality of prefabricated panelsaffixed together. Each panel comprises an insulated core (e.g.,polystyrene) having a plurality of strut wires passing therethrough,with the strut wires being connected to respective wire grids on eitherside of the insulated core. Rebar is then connected to the wire grids,and a layer of concrete (e.g., gunite or shotcrete) is applied over thewire grids and rebar so as to provide both structural integrity and anair-tight seal to the overcast.

While U.S. Pat. No. 5,879,231 may have provided for an overcaststructure having a shortened installation process and sealingimprovements over the previous concrete block and/or steel platepartitions, the need to provide and assemble the insulated cores, wiregrids, rebar, and concrete coating during installation still resulted ina complicated and time-consuming process. Accordingly, an effectiveovercast system requiring fewer materials and simplified installation isdesired.

SUMMARY OF THE INVENTION

It is an object of the present disclosure to provide an overcast systemand method that overcomes some or all of the above-describeddeficiencies of the prior art.

One non-limiting embodiment of the disclosure includes an overcastsystem having a first sidewall formed of one or more prefabricatedpanels, a second sidewall formed of one or more prefabricated panels,and a top member formed of one or more prefabricated panels. The topmember may span the width between the first sidewall and the secondsidewall. A fire-resistant coating is applied to at least a portion ofthe first sidewall, the second sidewall, or the top member to provide anair-tight, fire-resistant structure. Additionally, each of the one ormore prefabricated panels is formed from a composite material having oneor more structural studs embedded at least partially therein.

To facilitate securement of the one or more prefabricated panels to anadjacent panel, the one or more prefabricated panels may include atongue at one end thereof and define a groove at the other end thereoffor receiving a tongue of an adjacent panel. A brace may be secured tothe first sidewall and the top member to add further structuralintegrity to the overcast system.

The composite material may be an expanded polystyrene (EPS). Each of theone or more prefabricated panels may include two or more structuralstuds embedded at least partially therein. The structural studs may beS-shaped steel studs.

In one embodiment, a wire mesh is applied to at least a portion of asurface of the first sidewall, the second sidewall, and the top member.The fire-resistant coating may be a fiber-reinforced composite rockcoating.

One or more wing walls may be attached to the top side of the overcastsystem, which may include at least one of a staircase, a ramp, and aladder for traversing the overcast system.

Another non-limiting embodiment of the disclosure includes a method offorming an overcast system for mine ventilation, the method includesforming a first sidewall using one or more prefabricated panels, forminga second sidewall using one or more prefabricated panels, the secondsidewall spaced apart from the first sidewall and forming a top memberusing one or more prefabricated panels. The top member spans thedistance between the first sidewall and the second sidewall. The methodfurther includes applying a flame-resistant coating to at least aportion of the first sidewall, the second sidewall, and the top member.Each of the one or more prefabricated panels is formed from a compositematerial having one or more structural studs embedded at least partiallytherein. The method may additionally include securing the first and thesecond sidewalls to a bracket and attaching the bracket to a mine floor.

These and other features and characteristics of the present disclosure,as well as the methods of operation and functions of the relatedelements of structures and the combination of parts and economies ofmanufacture, will become more apparent upon consideration of thefollowing description and appended claims with reference to theaccompanying drawings, all of which form a part of the specification,wherein like reference numerals designate corresponding parts in variousfigures. It is to be expressly understood, however, that the drawingsare for the purpose of illustration and description only and are notintended as a definition of the limits of the disclosure. As used in thespecification and claims, the singular form of “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a perspective view of an overcast systeminstalled within an underground mine crosscut;

FIG. 2 is a perspective view of a prefabricated panel;

FIG. 3 is a partial top view of the prefabricated panel of FIG. 2;

FIG. 4 is a perspective view of an overcast system formed ofprefabricated panels;

FIG. 5 is a partial cross-sectional view of the overcast system of FIG.4 taken along line 5-5 as installed in a mine entry;

FIG. 6 is a side view of an overcast system having connecting cross-barsbetween prefabricated panels and a wire mesh thereon;

FIG. 7 is a partial perspective view of an overcast system having aribbed expanded metal form thereon;

FIG. 8 is a side view of the application of a spray-on coating on anovercast system; and

FIG. 9 is a perspective view of the spray-on coating of FIG. 8.

DESCRIPTION OF THE INVENTION

For purposes of the description hereinafter, the terms “upper”, “lower”,“right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “lateral”,“longitudinal”, and derivatives thereof shall relate to the invention asit is oriented in the drawing figures. However, it is to be understoodthat the disclosure may assume various alternative variations and stepsequences, except where expressly specified to the contrary. It is alsoto be understood that the specific devices and processes illustrated inthe attached drawings, and described in the following specification, aresimply exemplary aspects of the disclosure. Hence, specific dimensionsand other physical characteristics related to the aspects disclosedherein are not to be considered as limiting.

Referring to FIG. 1, an overcast system 100 in accordance with an aspectof the present disclosure is shown schematically in a crosscut of anunderground mine. Overcast system 100 comprises a first sidewall 102, asecond sidewall 104, and a top member 106. As will be set forth in moredetail hereinbelow, the first sidewall 102, the second sidewall 104, andthe top member 106 may each be formed of a plurality of interconnectableprefabricated panels. The first and second sidewall 102, 104 and topmember 106 are installed at an intersection between two passageways (Aand B) to define a first opening 105 a and an overpass 105 b. Airpassing through the opening 105 a along a first path (e.g., directions Ain FIG. 1) is prevented from mixing with air traveling along a secondpath (e.g., directions B in FIG. 1) which includes overpass 105 b. Thefirst sidewall 102 and the second sidewall 104 are formed to be widerthan the entry/opening that they are configured to block. For example,if the entry/opening width along each passageway is 16 feet, the firstsidewall 102 and the second sidewall 104 may be slightly wider (e.g., 20to 24 feet) so as to improve the air sealing qualities of the system100.

The top member 106 is constructed to span both the entire length of thefirst sidewall 102 and the second sidewall 104 and the width betweenrespective sidewalls 102, 104, thereby effectively forming the opening105 a in the first passageway A. While air moving through the secondpassageway B is blocked by sidewalls 102, 104 from mixing with the airmoving through the first passageway A, the air moving through the secondpassageway B is allowed to move over the top member 106 via overpass 105b to continue along the length of the second passageway B. Optional wingwalls 108, 110 may be constructed and attached upon the top member 106to further direct air through the second passageway B and minimize airmoving through the second passageway B from mixing with air movingthrough the first passageway A, and vice versa. Sidewalls 102, 104, topmember 106, and wing walls 108, 110 may be formed of a plurality ofprefabricated panels, as will be discussed hereinbelow. Furthermore, apair of staircases 112, 114 may be installed with system 100 so as toallow personnel to traverse the overpass 105 b of overcast system 100and move through the second passageway B. While staircases 112, 114 areshown, it is to be understood that other features such as ramps,ladders, etc. may be utilized to enable travel over the overcast system100. Details of the components of sidewalls 102, 104 and top member 106are described hereafter.

Referring now to FIG. 2 and FIG. 3, a prefabricated panel 200 inaccordance with an aspect of the present disclosure is shown. Asdiscussed above with respect to FIG. 1, sidewalls 102, 104 and topmember 106 may be produced from at least one prefabricated panel 200, aplurality of which may be interconnected to form the overcast system100. Panel 200 includes sidewalls 202 and top side 204 and may beconfigured for a tongue-and-groove connection to an adjacent panel (orpanels). Specifically, one end of panel 200 defines a groove 206, whilethe opposite end of panel 200 includes a tongue 208, thereby enablingconstruction of a robust and substantially air-tight connection betweenadjacent panels.

Panel 200 includes a wall 201 that may be formed from athermally-efficient material, such as expanded polystyrene (EPS). Eachpanel 200 further includes a pair of studs, such as S-shaped studs 210,212, which may be formed from steel. Studs 210, 212 may define openings213 to accommodate other structural components, as described below. Theopenings 213 may be slots, circles, or any other shape adapted toreceive the structural components. An example of such a prefabricatedpanel is the ACCEL-E® Steel Thermal Efficient Panel from Syntheon, Inc.(Pittsburgh, Pa.). As shown in FIG. 3, a first portion 214A of each stud210, 212 is embedded within the panel 200, while a second portion 214Bextends outside of panel 200 to form a useable stud on one of thesidewalls 202. In this way, S-shaped studs 210, 212 provide strength tothe panel 200 without the need for additional reinforcements, such asrebar, wire grids, or cement coatings. Furthermore, fasteners are notneeded to affix studs 210, 212 to panel 200, thereby simplifying theinstallation process.

Each stud 210, 212 is for example, spaced two feet apart. However, it isto be understood that the spacing of studs 210, 212 may be altered asmore or fewer studs may be utilized in each panel 200. Furthermore, eachpanel 200 may come in standard widths (e.g., four feet), but may havecustomizable lengths so as to accommodate different passageway heights,spans, etc. With such standard widths, a plurality of prefabricatedpanels 200 may be condensed onto a single pallet to be transportedthrough the mine passageways to the installation site, thereby reducingthe time and effort needed to deliver the materials to be used inconstruction of an overcast system.

Referring to FIG. 4, an overcast system utilizing a plurality of panels200 in accordance with an aspect of the present disclosure is shown.Each panel 200 is configured to be interconnected to an adjacent panel200 via at least the tongue-and-groove connection discussed above withrespect to FIG. 2. In FIG. 4, a pair of panels 200 are disposed adjacentone another so as to form each respective sidewalls 102, 104, whileanother pair of panels 200 are disposed adjacent one another and atopeach sidewall 102, 104 so as to form a top member 106 of the overcastsystem 100.

Referring to FIG. 5, an “L” bracket or corner brace 116 may be fastenedbetween the first sidewall 102 and the top member 106 and between thesecond sidewall 104 and the top member 106 to provide further structuralreinforcement to the system 100. The corner brace 116 may be onecontinuous bracket spanning the length of the top member 106 or mayinclude a plurality of brackets. The corner brace 116 may be secured tosidewalls 102, 104 and top member 106 by one or more self-tapping screwsor any other suitable attachment method commonly known in the art.

To securely install the overcast system 100, C-shaped channels 118 aresecured to the mine floor by extending one or more mine bolts 120,through the C-shaped channel 118 and into the mine floor F, which may bepre-drilled to receive the bolts 120. The panels 200 are then positionedin the channel 118 such as by sliding panels 200 into an open end of theC-shaped channel 118 and engaging the panels 200 thereto, for example,by extending one or more self tapping screws 215 to the studs 210, 212.The self tapping screws 215 may vary in length such that the screws 215are secured to either the wall 201 or the studs 210, 212, or both thewall 201 and the studs 210, 212. Securing the panels 200 to the minefloor F prevents the overcast system 100 from shifting when pressure inopening 105 a increases relative to overpass 105 b as may occur when airflows through first passageway A.

As shown in FIG. 6, the overcast system 100 may include reinforcementstructures. A pair of panels 200 having respective walls 201 are shownadjacent one another, with S-shaped studs 210, 212 extending therefrom.To more securely hold the respective panels together, one or morecross-bar connectors 215 extend between a stud 212 of one panel and astud 210 of the adjacent panel. The cross-bar connectors 215 may have afixed head and a terminal nut threaded thereon to engage studs 210, 212.Rotation of the terminal nut relative to the studs 210, 212 adjusts thedistance between the fixed head and the terminal nut to transition thecross-bar 215 from an un-tightened position in which the cross-bar ismoveable relative to the studs 210, 212 (FIG. 4 and FIG. 6) to atightened position in which the fixed head and the terminal nut preventmovement of the cross-bar relative to the shaft to which the cross-bar215 is attached. This assures that the panels do not separate, therebyimproving the strength and air-tight qualities of the overcaststructure. It is to be understood that any reasonable means of holdingthe adjacent panels together is suitable in accordance with thedisclosure.

In addition, as shown in FIG. 6, panels 200 may be at least partiallycovered with wire mesh 220 disposed at or near a surface of the panels.Unlike prior art panels, the wire mesh 220 is not meant to provideincreased structural integrity to the panels themselves. Instead, thewire mesh 220 may serve as a structural support for a fire-resistantspray-on coating to be added after construction of the overcaststructure. The wire mesh 220 may also act to provide an increasedsurface area for the spray-on coating to adhere upon when applied to theovercast structure. By way of a non-limiting example, the wire mesh 220may be attached to the steel studs 210, 212 using, for example,self-drilling screws.

The wire mesh 220 shown in FIG. 6 is shown as a 1-inch by 1-inch mesh,but it is to be understood that other forms of mesh or structuralsupport for the spray-on coating may be used in accordance with variousaspects of the disclosure. For example, referring to FIG. 7, a ribbedmetal form 222 such as Stayform® available from Alabama Metal IndustryCorporation (Birmingham, Ala.), may be attached to interior surfaces ofpanels 200 via suitable fasteners (screws, bolts or the like), notshown. Added surface members (wire mesh, metal forms, etc.) may beapplied to one or more interior or exterior surfaces of panels 200.Also, while not shown, a wider mesh, such as a 4-inch by 4-inch mesh,may be used. Alternatively, no mesh or other structural support may beused, and the spray-on coating may be applied directly to the panels200.

Referring now to FIG. 8 and FIG. 9, an overcast system 1000 having aspray-on coating is shown. As discussed above, the spray-on coating ispreferably a fire-resistant coating. An example of a suitable coating isa cementitious, fiber-reinforced composite rock coating material, suchas J-CRETE® from Jennmar (Pittsburgh, Pa.). J-CRETE® is a high-strength(10,000 psi) Thin Spray-on Liner (TSL) that provides sealing andflame-resistant qualities to the overcast system 1000. As shown in bothFIG. 8 and FIG. 9, the spray-on coating is applied to at least a portionof and may be applied to all surfaces of overcast system 1000. Unlikeprevious overcast systems utilizing a concrete-based coating, thespray-on coating of overcast system 1000 does not primarily act as astructural reinforcement for the system. Rather, the spray-on coating ofovercast system 1000 acts to seal and bond the prefabricated panels intoa single-acting, air-tight, fire-resistant structure.

While not shown in FIG. 9, overcast system 1000 may further comprise aplurality of foam blocks placed between adjacent studs on the top sideof the system prior to application of the spray-on coating. The foamblocks may be sized to provide an even and level platform surface on thetop side such that after the spray-on coating is applied and cured, asuitable walking surface is formed on the top member 106 of the overcaststructure 100.

Although the disclosure has been described in detail for the purpose ofillustration based on what are currently considered to be the mostpractical and preferred aspects, it is to be understood that such detailis solely for that purpose and that the disclosure is not limited to thedisclosed aspects, but, on the contrary, is intended to covermodifications and equivalent arrangements. For example, it is to beunderstood that the present disclosure contemplates that, to the extentpossible, one or more features of any aspect can be combined with one ormore features of any other aspect.

The invention claimed is:
 1. An overcast system comprising: a firstsidewall formed of one or more prefabricated panels; a second sidewallformed of one or more prefabricated panels; a top member formed of oneor more prefabricated panels, wherein the top member spans the widthbetween the first sidewall and the second sidewall; and a fire-resistantcoating applied to the first sidewall, the second sidewall, and the topmember; wherein each of the one or more prefabricated panels is formedof a composite material having one or more structural studs embedded atleast partially therein.
 2. The overcast system of claim 1, wherein thecomposite material is expanded polystyrene (EPS).
 3. The overcast systemof claim 1, wherein the one or more structural studs are S-shaped steelstuds.
 4. The overcast system of claim 1, wherein each of the one ormore prefabricated panels comprises two structural studs embedded atleast partially therein.
 5. The overcast system of claim 1, wherein thefire-resistant coating is fiber-reinforced composite rock coating. 6.The overcast system of claim 1, further comprising one or more wingwalls attached to the top member.
 7. The overcast system of claim 1,further comprising at least one of a staircase, a ramp, and a ladder. 8.The overcast system of claim 1, wherein each of the one or moreprefabricated panels includes a tongue at one end thereof and defines agroove at another end thereof for receiving a tongue of another panel.9. The overcast system of claim 1, further comprising a wire meshapplied to at least a portion of a surface of the first sidewall, thesecond sidewall, or the top member.
 10. The overcast system of claim 1,further comprising a brace secured to the first sidewall and the topmember.
 11. The overcast system of claim 1, further comprising a bracketsecured to a sidewall, the bracket being configured for attachment to amine floor.
 12. A method of forming an overcast system for mineventilation, the method comprising: forming a first sidewall using oneor more prefabricated panels; forming a second sidewall using one ormore prefabricated panels, the second sidewall spaced apart from thefirst sidewall; forming a top member using one or more prefabricatedpanels, the top wall spanning the distance between the first sidewalland the second sidewall; and applying a flame-resistant coating to atleast a portion of the first sidewall, the second sidewall, or the topmember; wherein each of the one or more prefabricated panels is formedfrom a composite material having one or more structural studs embeddedat least partially therein.
 13. The method of claim 11, furthercomprising securing the first and the second sidewalls into a bracketattached to a mine floor.